Miniaturization of control boards with flexibility in desposition of parts and wiring

A board main body part has a multilayer structure with even-numbered layers including a first layer formed on a surface part on one side and a second layer formed on a surface part on the other side. On both of the first layer and the second layer, a low voltage region in which a low voltage circuit is disposed, a high voltage region in which high voltage circuits are disposed, and an insulating region in which the low voltage region is electrically isolated from the high voltage region are formed. At least a part of a first high voltage circuit is disposed in a first-layer high voltage region formed on the first layer, and at least a part of a second high voltage circuit is disposed in a second-layer high voltage region formed on the second layer.